Abnormalities of fatty acid metabolism are considered to be important contributors to the adverse health consequences of upper body/visceral obesity. We propose to assess the effects of insulin on splanchnic FFA metabolism in visceral obesity and to investigate intramuscular fatty acid kinetics using newly developed stable isotope methodology. The objective of this protocol is to improved insulin action with respect to glucose metabolism, whether accomplished by exercise training/weight loss or via troglitazone treatment is associated with improvements in insulin action on FFA and intramuscular fatty acid metabolism in viscerally obese humans.